The invention pertains to a process or method for making substrates with textured or structured metalizations. The invention also pertains to a holding and fastening element for the use in such a method.
The manufacture of substrates with textured or structured metalizations for the use as printed boards for electrical devices are known in a variety of models. The texturing generally takes place using a masking or etching process, for example.
The substrates according to the present invention are, for example, ceramic/metal substrates that in their simplest form consist of a ceramic layer that is provided with a metalization on one surface, but preferably on both surfaces, for example in the form of a metal foil applied to the surface.
It is known that these metalizations required for conductors, connections etc. on ceramic, e.g. on aluminum-oxide ceramic are produced by means of the so-called xe2x80x9cDCB processxe2x80x9d (direct copper bond technology), using metal or copper foils or metal or copper sheets forming the respective metalization that have a layer or a coating (melt-on layer) consisting of a chemical compound of the metal and a reactive gas, preferably oxygen. In this process, which is described for example in U.S. Pat. No. 3,744,120 or DE-PS 23 19 854, this layer or coating (melt-on layer) forms a eutectic system with a melting temperature under the melting temperature of the metal (e.g. copper), so that by application of the foil on the ceramic and by heating all layers these can be connected to each other, by melting on the metal or copper essentially only in the area of the melt-on layer or oxide layer.
This DCB technology exhibits the following processing stages:
Oxidation of a copper foil in such a manner that an even copper oxide layer is formed;
Application of the copper foil to the ceramic layer;
Heating of the compound to a processing temperature between approximately 1025 and 1083xc2x0 C., e.g. to approx. 1071xc2x0 C.; Cooling to room temperature.
The substrates according to the present invention are also, for example, such substrates that consist of a base and/or insulating layer made of plastic that is provided with a metalization formed by a metal foil on at least one surface area. The substrates according to the present invention are also known substrates in which a thin insulating layer, for example of plastic, is applied to one base layer made of metal, for example aluminum and which (insulating layer) bears the metalization in the form of a metal foil, for example.
An object of the invention is to present a new process enabling texturing in an extremely efficient nature, especially using known masking and etching technologies.
In order to attain this object, a process or method for making substrates with textured or structured metalizations is characterized in that for texturing the metalizations of at least two substrates in one process, the two substrates are fastened tightly together in a removable manner, by means of at least one holding or fastening means on one surface side of each substrate, and then, the texturing of the metalizations is performed on the other free outer surface sides of the substrates.
A holding or fastening element for use in such a process is characterized by being formed as a ring or plate-like body made of a sealed material, for example of an elastic or rubber-like material, whereby the body has at least one opening that is closed on its periphery and a bearing surface on each of two opposite sides encompassing the opening.
The process according to the present invention offers the advantage, among other things, that at least two substrates or printed boards can be textured at the same time in one process, each on only one surface (outer surface side), whereby the other surface (inner surface side) or a metalization located there is not affected. The invention offers the additional advantage that a one-sided texturing of printed boards or substrates is possible using the existing equipment normally used for two-sided texturing, so that the same equipment can be used for one-sided and two-sided texturing.